Fifty-five years ago today, NASA astronauts James A. McDivitt, David R. Scott, and Russell L. Schweickart splashed down 4.5 nautical miles from the USS Guadalcanal, concluding a successful 10-day Earth-orbital mission in space. In this image from March 13, 1969, a recovery helicopter hovers above the Apollo 9 spacecraft; the astronauts were still inside the command module.

Apollo 9 was the first crewed flight of the command/service module along with the lunar module. The mission’s three-person crew tested several aspects critical to landing on the Moon including the lunar module’s engines, backpack life support systems, navigation systems, and docking maneuvers.

See more photos from Apollo 9.

Image Credit: NASA